Science Buddies: "Ask an Expert"

Hi!!!

I am doing a science fair project on a project on family genetics. It's called "Pedigree Analysis: A Family Tree of Traits" from Science Buddies. I am supposed to show how 4 genetic traits are passed through my family. I want to do hair color, dettached or attached earlobes, widows peaks, and freckles. Are frekcles genetic? Also how would I know if red hair is recessive and blond is dominant or for any color?


Raenelson

Hello,

This is a great project! There is one thing that you should keep in mind, though. This model only works for genes that come in two forms (or alleles), with one exhibiting dominance over the other. These types of traits are known as Mendelian, after the scientist who discovered them in pea plants. The majority of traits, including hair color, are controlled by a variety of genes, so they are not Mendelian and they cannot be analyzed in your experiment. All of your traits are Mendelian except for hair color, which is determined by two genes, a brown/blonde gene in which blonde is recessive, and a red gene, in which the red phenotype is produced by two red alleles. This is a bit of an oversimplification, because the genes that produce various pigments also contribute to the darkness of hair, giving us the wide range of hair colors that we see. I would suggest sticking to the more simple Mendelian traits, such as your other three. Here is a list of Mendelian traits that you can track, http://en.wikipedia.org/wiki/List_of_Me ... _in_humans

Hope this helps,
Nithin T.